The function of the Animal Core is to produce and maintain all of the animals required for the scientific projects for this and several other Program Project grants. The specific services provided by the Animal Core personnel include: (1) production of transgenic and knockout mice; (2) production of large volumes of prion-infected hamster and mouse brains for purification; (3) performing experimental inoculations, neurologic scoring of animals, data collection, and tissue collection; (4) providing transportation of animals and tissues between the laboratory and the animal facility; (5) production of antibodies in mice and rabbits for experimental use; (6) providing all animal care and veterinary care; (7) providing cryopreservation of the various mouse lines. The Animal Core operates in two purpose-built facilities in the Hunters Point area of San Francisco, located approximately 3 miles from the main UCSF campus. The activities of the Animal Core are directed by Dr. Prusiner and Dr. Pierre Lessard, a laboratory animal veterinarian. Building 830B is a new nine-room transgenic mouse breeding facility that houses our large breeding colony. Building 830 houses all the experimental animals in 21 rooms, under BSL-2 and BSL-3 biocontainment. It houses, on average, 20,000 mice, 400 hamsters, and 3 rabbits. The facility is inspected bi-annually by the USDA and UCSF/IACUC.